Download presentation
Presentation is loading. Please wait.
1
DNA Questions What are nucleotides?
What are the four nitrogen containing bases on DNA? What is a double helix? Sketch it. What are the DNA base pairs? What is DNA? What type of biomolecule is DNA? What is replication? How might DNA relate to cancer?
2
The Big Ideas…Characteristics of Living Things
Made of Cells Reproduce (sexually or asexually) Have DNA (genetic information) Grow & Develop Need/Use Energy (metabolism) Respond to Environment Maintain Homeostasis (constant internal environment) Change Over Time (evolve) Form Systems & Have Systems (related parts) Structure & Function are Related
3
1953: The structure of the DNA molecule is first described.
As you can see from the model, the structure is basically a long, …twisted ladder type thing. 1953: The structure of the DNA molecule is first described.
4
KEY CONCEPT DNA structure is the same in all organisms.
5
The monomer for DNA is a nucleotide (Backbone & Bases)
Each nucleotide has three parts. nitrogen-containing base deoxyribose sugar phosphate group The base is the only part of a nucleotide that will change. phosphate group deoxyribose (sugar) nitrogen-containing base
6
The nitrogen bases are the only difference in the four nucleotides.
7
Those are the basic parts of DNA, but how did we figure out how it was put together?
8
Franklin’s x-ray images suggested that DNA was a double helix.
X-Ray Evidence In the early 1950’s a British scientist named Rosalind Franklin began to study DNA. Rosalind wanted to see what she was studying, so she took pictures of DNA with an X-ray. Franklin’s x-ray images suggested that DNA was a double helix. She does not receive much of the credit that she deserves for her research. TED-Ed: Rosalind Franklin - DNA's Unsung Hero
9
Chargaff’s Rules Erwin Chargaff was also studying the molecules present in DNA. He realized that the frequency of Adenine bases equaled Thymine bases / Same for Cytosine and Guanine. Number of A = Number of T Number of G = Number of C
10
Nucleotides always pair in the same way.
The base-pairing rules show how nucleotides always pair up in DNA. A pairs with T C pairs with G C G T A
11
Watson and Crick determined the three-dimensional structure of DNA by building models.
They realized that DNA is a double helix that is made up of a sugar-phosphate backbone on the outside with bases on the inside. 100 Greatest Discoveries - DNA
12
Bonding - Backbone is covalent bonds (STRONG).
Bonding - Bases are hydrogen bonds (weak). Hydrogen bond Covalent bond Sugar/Phosphate Backbone Nucleotide (monomer) Amoeba Sisters - DNA Structure CC - DNA & Replication
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.